Coiled Tubing Drilling (CTD) Technology was first implemented by Petronas Carigali Sdn. Bhd. (PCSB) in 2011 where 3 wells were successfully drilled via a pilot campaign. The rig-less technology allows through-tubing side tracking to be conducted from the existing completion. This approach provides access to marginal bypassed reserves, which otherwise would be uneconomical to be developed by conventional drilling. The entire project comprised plug and abandonment work, whipstock setting, window milling, drilling of the build & lateral sections and completion as per the well design.
The second phase of CTD project was successfully executed from June to December 2013 with all the three wells successfully drilled and completed as per the objectives. Different from pilot project modus operandi, Self-Elevating Workover Platform Vessel (SEWOP) also known as liftboat was utilized to assist the operation due to limited space and deck loading on the working platform. Such approach has minimized the platform modification required as well as significantly reducing the dependency of on good weather window. The self-propelled SEWOP option has proven to be a self-sufficient by providing the required deck space, accommodation and a stable platform in allowing the CTD operation to be carried out safely.
Highlights of the project was the successful drilling and completion of the world's first CTD multilateral well. Such strategy involved the drilling and completion of two separate targets from one mother bore with dual completion strings. In order to achieve the well objectives, the team was challenged with complicated well preparation work scope such as multiple stages of cementing job and accurate determination of the azimuth of the dual kick off points from the existing dual completions in order to avoid drilling collisions during side-tracking.
In addition, team has also managed to replicate the lessons learnt from the pilot project with 100% success rate in dual casing exit from the existing completion setup as well as conveying the completion to the target zone via CT through 3½" tubing with maximum inclination of 90 deg angle and dogleg ranges between 20–40 deg per 100 feet.
The second phase project utilized Reservoir Navigation System (RNS), Managed Pressure Drilling (MPD) and Rotary Steerable Motor (RSM) that optimized payzone drilled, improved drill-ability and smoothened long trajectory thus improving operational efficiency and success rate.
Despite multiple challenges, the project was able to be completed safely and successfully with all objectives met. The achievement was largely attributed to good teamwork, visible leadership, and constant support from management and effective communication between project team and service providers.
This paper discussed about the experiences, learning curves, challenges and lessons learnt of PCSB in making CTD technology viable and successful in offshore Malaysia.